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Powering a tas5630 from a transformer

Hernan Freschi
Prodigy 180 points
Other Parts Discussed in Thread: TAS5630B

I have several old transformers that can give me the 35V I need to power a TAS5630B (for 4ohms load at about 100W), but I have a doubt about peak voltage.

When you rectify and filter an AC voltage coming from a transformer, the voltage, unloaded, is Vrms*sqrt(2). When the supply is loaded, the voltage drops to about Vrms.

Since my TAS5630B consumes about 90mA at 24V with no load, I suppose the voltage in my supply will be rather high, so I'll have high losses on idle...right? But I don't know how this will affect transient response. During peaks, the filter capacitors will discharge and the voltage will drop. And I'll be getting supply noise.


How can I regulate the output of the transformer to meet the 35V requirement off a transformer? (Let's assume, for the sake of simplicity, that the transformer is 40V. So we have overhead for voltage dropout).

I know about the reference supply for TAS5630B, but I'm unable to get the inductors. I contacted Owolff... but they didn't answer back when I told them i just needed two of each. Oops :)

  • 0
    TI__Mastermind 37045 points

    Hi, Herman,

    You are probably aware of the apps note on the power supply already (link below). You would need PVCC and 12V supply for TAS5630B operation. For device reliability, you would want to ensure that the supply voltages do not go beyond the abs max rating. You are right about the higher idle loss at higher PVDD voltage. You maybe able to reduce the idle loss with LC filter design.

    http://www.ti.com/lit/ug/slou293c/slou293c.pdf

    Perhaps our community members can chime in on this..... 

    reg,

    Paul Chen.

    Audio Apps.

  • 0 in reply to user5276421
    Prodigy 180 points

    Paul,

    yeah I wanted to give that one a try. I can't buy it from you (import restrictions for devices that work off mains) so i wanted to build it. Owolff won't sell me the magnetics for it though.